> News
> Laser creates billions of antimatter particles
> Wednesday, 19 November 2008
> Cosmos Online
>
>
> Positron factory: Physicist Hui Chen sets up targets for the anti-
> matter experiment at the LLNL laser facility.
>
> Credit: LLNL
>
> SYDNEY: By shooting a laser through a gold disc no bigger than the
> head of a drawing pin, physicists have created more than 100
> billion particles of antimatter.
> The ability to create vast numbers of positrons in the laboratory
> opens the door to new avenues of research, they say. These include
> an understanding of the physics behind black holes, gamma ray
> bursts and why more matter than antimatter survived the Big Bang.
>
> Super-sized portion of positrons
>
> "We've detected far more antimatter than anyone else has ever
> measured in a laser experiment," said Hui Chen, a physicist at the
> Lawrence Livermore National Laboratory (LLNL) in California, U.S.,
> who led the experiment. "We've demonstrated the creation of a
> significant number of positrons using a short-pulse laser."
>
> Previous experiments made smaller quantities of positrons using
> lasers and paper-thin targets - but new simulations showed that
> millimetre-thick gold could be a far more effective source, said
> the researchers, who report their finding this week at the American
> Physical Society's Division of Plasma Physics Meeting in Dallas,
> South Carolina.
>
> Chen and her team used a short, ultra-intense laser to irradiate a
> millimetre-thick gold target.
>
> In the experimental set-up, the laser ionises and accelerates
> electrons, which are driven right through the gold target. On their
> way, the electrons interact with the gold nuclei, which serve as a
> catalyst to create positrons.
>
> Electron's opposite number
>
> The electrons give off packets of pure energy, which decay into
> matter and antimatter, following the predictions of Einstein's
> famous equation that relates matter and energy. By concentrating
> the energy in space and time, the laser produces positrons more
> rapidly and in greater density than ever before in the laboratory.
>
> Positrons are the antimatter equivalent to the electron, and behave
> in a similar way, though they have the opposite charge (see, New
> twist to matter-antimatter mystery, Cosmos Online).
>
> The researchers took advantage of this property to detect them, by
> using a typical device to detect electrons (a spectrometer) and
> equipping it to detect particles with opposite polarity as well.
>
> "By creating this much antimatter, we can study in more detail
> whether antimatter really is just like matter, and perhaps gain
> more clues as to why the universe we see has more matter than
> antimatter," said LLNL team member Peter Beiersdorfer.
>
>
> "We've entered a new era," Beiersdorfer added. "Now, that we've
> looked for it, it's almost like it hit us right on the head. We
> envision a centre for antimatter research, using lasers as cheaper
> antimatter factories."
>
> Particles of antimatter are almost immediately annihilated by
> contact with normal matter, and converted to pure energy in the
> form of gamma rays.
>
> There is considerable speculation as to why the observable universe
> appears to be almost entirely matter, whether other universes could
> be almost entirely antimatter, and what might be possible if
> antimatter could be harnessed.
>
> Product of energetic celestial events
>
> Normal matter and antimatter are thought to have been in balance in
> the very early universe, but, due to a mysterious 'asymmetry', the
> antimatter decayed or was annihilated, and today very little remains.
>
> Over the years, physicists had theorised about antimatter, but it
> wasn't confirmed to exist experimentally until 1932.
>
> High-energy cosmic rays impacting Earth's atmosphere produce minute
> quantities of antimatter in the resulting jets, and physicists have
> learned to produce modest amounts of anti-matter using traditional
> particle accelerators and smaller laser set-ups in the lab.
>
> Antimatter may also be churned our in regions like the centre of
> the Milky Way and other galaxies, where very energetic celestial
> events occur. The presence of the resulting antimatter is
> detectable by the gamma rays produced when positrons are destroyed
> when they come into contact with nearby matter.
>
> ###
> With the Lawrence Livermore National Laboratory.
>
>
> [Non-text portions of this message have been removed]
